Information
PIM is a routing protocol used to build multicast distribution trees for forwarding multicast traffic across the network infrastructure. PIM traffic must be limited to only known PIM neighbors by configuring and binding a PIM neighbor filter to those interfaces that have PIM enabled. If a PIM neighbor filter is not applied to those interfaces that have PIM enabled, unauthorized switches can join the PIM domain, discover and use the rendezvous points, and also advertise their rendezvous points into the domain. This can result in a denial of service by traffic flooding or result in the unauthorized transfer of data.
NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.
Solution
Configure neighbor prefix lists to only accept PIM control plane traffic from documented PIM neighbors.
Step 1: Configure prefix list for each PIM neighbor.
SW1(config)# ip prefix-list PIM_NEIGHBOR seq 5 permit 10.1.12.2/32
SW1(config)# ip prefix-list PIM_NEIGHBOR deny 0.0.0.0/0 le 32
Step 2: Apply a prefix to all interfaces enabled for PIM.
SW1(config)# int e2/1
SW1(config-if)# ip pim neighbor-policy prefix-list PIM_NEIGHBOR
SW1(config-if)# end